JP5421826B2 - Low temperature liquefied gas pump - Google Patents

Description

  The present invention relates to a low-temperature liquefied gas pump, and more particularly to a low-temperature liquefied gas pump used for increasing or pumping a low-temperature liquefied gas such as liquid oxygen, liquid nitrogen, liquid argon, or liquefied natural gas.

  As a low-temperature liquefied gas pump for boosting a low-temperature liquefied gas such as liquid oxygen or liquid nitrogen, a pump using a magnet pump that does not cause leakage of the low-temperature liquefied gas is known (for example, see Patent Document 1). .

JP 2006-348877 A

  In the case of a low-temperature liquefied gas pump that handles a low-temperature liquefied gas of about −160 to −196 ° C., assembly and maintenance of the pump must be performed at room temperature, and the temperature difference from when the low-temperature liquefied gas is handled is 200 ° C. or more. Therefore, even when components with different thermal expansion coefficients are used, the pump spindle, rolling bearing, bearing holder, holder mounting part, and pump casing axes must be on the same straight line regardless of temperature changes. It has been. Also, it must be avoided that a component having a large low temperature shrinkage tightens another component.

  Therefore, an object of the present invention is to provide a low-temperature liquefied gas pump in which axes such as a pump main shaft and a rolling bearing can be reliably and easily arranged on the same straight line.

  In order to achieve the above object, the low-temperature liquefied gas pump of the present invention rotatably supports a pump main shaft provided with an inducer and an impeller via a pair of rolling bearings inside the pump casing, and the pump main shaft rotates. In the low-temperature liquefied gas pump that discharges the low-temperature liquefied gas sucked into the inducer from the liquid inlet of the pump casing by the impeller and discharges it from the liquid outlet of the pump casing, the magnet coupling that transmits the rotation of the drive source to the pump main shaft And a pair of bearing holders for holding the pair of rolling bearings, respectively, and the pump casing is provided with a pair of holder mounting portions for mounting the bearing holders. The pump main shaft and the pump casing are positioned at a coaxial position. It is characterized in that the pin hole for inserting the alignment pin when is formed the.

  Furthermore, in the low-temperature liquefied gas pump of the present invention, the impeller is a two-stage impeller including a first-stage impeller disposed on the inducer side and a second-stage impeller disposed on the magnet coupling side, The pair of rolling bearings includes a first rolling bearing disposed between the first stage impeller and the second stage impeller, and a second rolling bearing disposed between the second stage impeller and the magnet coupling. The low-temperature liquefied gas on the second stage impeller side is supplied for lubrication of the first rolling bearing through a labyrinth seal that seals the pump main shaft and the pump casing between the second stage impeller and the first rolling bearing. A liquefied gas passage for lubrication discharged from the first rolling bearing to the first stage impeller side is provided.

  Further, the holder mounting portion is a holder accommodating recess for accommodating the bearing holder, and a gap for absorbing thermal expansion and contraction is provided between the inner surface of the holder accommodating recess and the outer surface of the bearing holder. It is characterized by.

  According to the low-temperature liquefied gas pump of the present invention, the holder mounting portion of the pump casing and the bearing holder that respectively holds the rolling bearing can be positioned by the alignment pin, so that the shaft core of each constituent member can be surely aligned. it can. Further, since lubrication is performed with a low-temperature liquefied gas, impurities do not enter, and a large temperature difference can be accommodated by providing a gap for absorbing thermal expansion and contraction.

It is sectional drawing which shows one example of a low-temperature liquefied gas pump of this invention. Similarly it is an expanded sectional view of an important section. It is a perspective view which shows the example of 1 form of a bearing holder. It is a perspective view which shows the other example of a form of a bearing holder. It is sectional drawing which shows the other example of a low temperature liquefied gas pump of this invention.

  The low-temperature liquefied gas pump shown in FIG. 1 is a two-stage boosting type low-temperature liquefied gas pump, and a pump main shaft 13 is rotatably supported in a pump casing 11 via a pair of rolling bearings (bearings) 12 and 12. The base end portion 13 a of the pump main shaft 13 is connected to a motor 15 serving as a drive source via a magnet coupling 14.

  An inducer 16 and a first stage impeller 17 are provided at the tip end portion 13 b of the pump main shaft 13, and a second stage impeller 18 is provided at an intermediate portion of the pump main shaft 13. In addition, a liquid inlet 19 is provided on the leading end side of the inducer 16 of the pump casing 11, a suction pipe (not shown) is connected, and a liquid outlet 20 is provided on the outer periphery of the second stage impeller 18 of the pump casing 11. And a discharge pipe (not shown) is connected.

  A liquid passage 21 that bypasses the outside of the second stage impeller 18 is provided between the outer peripheral part of the first stage impeller 17 and the inner peripheral part of the second stage impeller 18. A shaft is sealed between the impeller 17 and the second stage impeller 18 by a labyrinth seal 22 that allows a slight liquid flow.

  The first rolling bearing 12 on the first stage impeller 17 side is held by the first bearing holder 23 and the second rolling bearing 12 on the magnet coupling 14 side is held by the second bearing holder 24, respectively. The first bearing holder 23 on the side is mounted on a first holder mounting portion 25 that is open on the first stage impeller 17 side of the pump casing 11, and the second bearing holder 24 on the magnet coupling 14 side is a magnet. It is mounted on a second holder mounting portion 26 that is open on the coupling 14 side.

  As shown in FIGS. 2 and 3, the first bearing holder 23 on the first stage impeller 17 side is formed in a disk shape having a convex cross section with a small diameter disk portion 23 b protruding from one side of the large diameter disk portion 23 a. The first holder mounting portion 25 of the pump casing 11 to which the first bearing holder 23 is mounted has a large-diameter disk portion receiving recess 25a having an inner diameter slightly larger than the outer diameter of the large-diameter disk portion 23a, and a large diameter A small-diameter disk portion receiving recess 25b having a smaller diameter than the disk portion receiving recess 25a and a slightly larger inner diameter than the outer diameter of the small-diameter disk portion 23b.

  On the inner periphery of the first bearing holder 23, a pump spindle insertion port 23c having an inner diameter larger than the outer diameter of the pump spindle 13 is provided on the distal end side (holder mounting portion insertion side), and the pump spindle insertion port 23c On the base end side (first stage impeller 17 side), a bearing fitting recess 23e having a diameter larger than that of the pump main shaft insertion port 23c via the step part 23d and having an inner diameter corresponding to the outer diameter of the rolling bearing 12 is provided. ing. Further, the large-diameter disk portion 23a of the first bearing holder 23 is provided with an annular groove 23f into which the cylindrical seal portion 17a protruding from the rear inner peripheral portion of the first stage impeller 17 is inserted. Usually, a labyrinth groove is formed on the outer peripheral surface of the cylindrical seal portion 17a. Between the outer peripheral surface of the cylindrical seal portion 17a having the labyrinth groove and the inner peripheral surface on the large-diameter disk portion 23a side of the annular groove 23f. A labyrinth seal for sealing the low-temperature liquefied gas is formed in the gap.

  The large-diameter disk portion 23a of the first bearing holder 23 is provided with a plurality of bolt insertion holes 23g on one circumference at equal intervals, and the large-diameter disk portion accommodating recess 25a of the first holder mounting portion 25. A plurality of female screw holes 25d are provided at positions corresponding to the bolt insertion holes 23g in a holder mounting surface 25c formed in a step portion between the small diameter disk portion accommodating recess 25b.

  The rolling bearing 12 is inserted into the bearing fitting recess 23e of the first bearing holder 23, and is fitted and held in a state where the outer ring front end surface of the rolling bearing 12 is in contact with the step portion 23d of the first bearing holder 23. The The first bearing holder 23 fitted with the rolling bearing 12 in the bearing fitting recess 23e is inserted into the first holder mounting portion 25 of the pump casing 11 so that the axis of the pump main shaft 13 and the axis of the rolling bearing 12 coincide. The first holder mounting portion 25 is screwed into the female screw hole 25d of the holder mounting surface 25c of the first holder mounting portion 25 and tightened with the mounting bolt 27 inserted in the bolt insertion hole 23g of the large-diameter disk portion 23a. It is attached to.

  With the first bearing holder 23 mounted at a predetermined position of the first holder mounting portion 25, the outer peripheral surface of the large-diameter disk portion 23a of the first bearing holder 23 and the large-diameter disk portion receiving recess 25a of the first holder mounting portion 25. Between the inner peripheral surface of the first bearing holder 23 and between the outer peripheral surface of the small-diameter disk portion 23b of the first bearing holder 23 and the inner peripheral surface of the small-diameter disk portion receiving recess 25b of the first holder mounting portion 25. For this reason, the respective clearances S are provided.

  On the other hand, the first bearing holder 23 is mounted on the first holder mounting portion 25 and adjusted and positioned so that the axis of the pump main shaft 13 and the axis of the rolling bearing 12 coincide with each other in the room temperature state when the pump is assembled. A plurality of pin holes 30 a and 30 b for inserting the alignment pin 29 from the large-diameter disk portion 23 a of the first bearing holder 23 to the holder mounting surface 25 c of the first holder mounting portion 25 in a state of being temporarily fixed by the bolts 27. Drilled in a direction parallel to the axis of the pump main shaft 13. The pin holes 30a and 30b are formed in a state where the first holder mounting portion 25 of the pump casing 11 and the first bearing holder 23 fitted with the rolling bearing 12 are positioned, and the pin holes 30a and 30b and the alignment pin 29 are positioned. Is set so that there is almost no play, and when the pump is assembled after disassembly, one end of the alignment pin 29 is inserted into the pin hole 30b formed in the holder mounting surface 25c and the other end is protruded Thus, the first bearing holder 23 is inserted into the first holder mounting portion 25 while inserting the alignment pin 29 protruding from the holder mounting surface 25c into the pin hole 30a formed in the large-diameter disk portion 23a. The bearing holder 23 can be reliably and easily disposed at a predetermined position in the first holder mounting portion 25. Thereafter, by tightening the mounting bolts 27 in a predetermined order, the first position is set to a predetermined position in the first holder mounting portion 25, that is, a position where the axis of the pump main shaft 13 and the axis of the rolling bearing 12 coincide. The bearing holder 23 can be mounted and fixed.

  The second bearing holder 24 and the second holder mounting portion 26 on the magnet coupling 14 side are also formed in substantially the same manner as the first bearing holder 23 and the first holder mounting portion 25, and the second holder mounting is performed in the same procedure. The second bearing holder 24 is fixed to the portion 26. As with the first bearing portion, the outer peripheral surface of the large-diameter disk portion of the second bearing holder 24 and the second holder mounting portion with the second bearing holder 24 mounted at a predetermined position of the second holder mounting portion 26. 26 between the inner peripheral surface of the large-diameter disk portion accommodating recess and the outer peripheral surface of the small-diameter disk portion of the second bearing holder 24 and the inner peripheral surface of the small-diameter disk portion accommodating recess of the second holder mounting portion 26. Are provided with the same gaps for absorbing thermal expansion and contraction as the gaps S.

  After the pump is assembled, the rolling bearing 12 on the first stage impeller 17 side is prevented from coming off by the central portion of the first stage impeller 17 coming into contact with the inner ring, and the rolling bearing 12 on the magnet coupling 14 side is attached to the pump casing 11. The fixing member 28 that holds the outer ring on the outer surface side is fixed with bolts to prevent it from coming off. In addition, although illustration is abbreviate | omitted, the rolling bearing 12 by the side of the magnet coupling 14 may be made to be prevented from coming off by fixing the inner ring side with a bearing nut.

  Further, a shaft between the first stage impeller 17 and the second stage impeller 18 in the pump main shaft 13 is sealed with a labyrinth seal 22 that allows a slight liquid flow, and a relatively high pressure and low temperature on the second stage impeller 18 side. By forming the liquefied gas so as to slightly flow toward the relatively low pressure first stage impeller 17 side, the liquefied gas rolls from the second stage impeller 18 side through the part of the labyrinth seal 22 and the part of the pump main shaft insertion port 23c. A liquefied gas passage for lubrication from the rolling bearing 12 to the first stage impeller 17 can be provided so as to reach the bearing 12, and the rolling bearing 12 on the first stage impeller 17 side can be lubricated by the low temperature liquefied gas. Similarly, the rolling bearing 12 provided on the magnet coupling 14 side is covered with a can 14a of the magnet coupling 14 mounted on the outside of the rolling bearing 12, and the second bearing holder 24, the pump main shaft 13, and the like. The low-temperature liquefied gas flows into the can 14a of the magnet coupling 14 from the flow path formed between them, and the can 14a is filled with the low-temperature liquefied gas. Lubrication is ensured.

  Further, between the outer peripheral surface of the first bearing holder 23 and the inner peripheral surface of the first holder mounting portion 25, and between the outer peripheral surface of the second bearing holder 24 and the inner peripheral surface of the second holder mounting portion 26. By providing the gaps S for absorbing thermal expansion and contraction, even if the temperature of the pump casing 11 decreases and the first holder mounting portion 25 and the second holder mounting portion 26 shrink, the first bearing holder 23 and the second 2 The bearing holder 24 is tightened so that the axis of the rolling bearing 12 does not go wrong. Therefore, even if the amount of contraction varies depending on the material of the pump casing 11, the first bearing holder 23, and the second bearing holder 24 due to the change to the low-temperature liquefied gas having a different temperature, a pair of rolls at a predetermined position in the pump casing 11. The bearings 12 and 12 can be reliably held, and the first stage impeller 17 and the second stage impeller 18 can be kept in a stable rotational state by the pump main shaft 13.

  Moreover, since the rolling bearings 12 and 12 are arranged inside the pump casing 11 using the magnet coupling 14 and the low-temperature liquefied gas whose pressure is increased by the pump itself is used for lubrication of the rolling bearing, the bearing is used for the pump casing 11. The pump can be reduced in size as compared with the one provided outside, and the leakage of the low-temperature liquefied gas can be completely prevented, and the low-temperature liquefied gas can be prevented from being contaminated by the lubricating oil. Furthermore, maintenance work can be reduced, and the cost required for maintenance can also be reduced.

  In the present invention, as shown in FIG. 4, the peripheral wall of the bearing fitting recess 23 e of the first bearing holder 23 and the peripheral wall of the bearing fitting recess of the second bearing holder 24 may be used as the outer ring of the rolling bearing 12. As shown in FIG. 5, it can also be applied to a one-stage boosting type low-temperature liquefied gas pump. 4 and 5, the same components as those of the low-temperature liquefied gas pump shown in the above-described embodiment are given the same reference numerals, and detailed description thereof is omitted.

  In the case of a one-stage boosting type low temperature liquefied gas pump as shown in FIG. 5, although not shown, the first bearing and the second bearing are communicated from the discharge port of the first stage impeller 17 for lubricating the rolling bearing. A passage for supplying a low-temperature liquefied gas is provided in the gap, and the rolling bearings 12 and 12 can be lubricated with the low-temperature liquefied gas. Further, in order to reduce the thrust force and radial force applied to the bearing, a balance hole or a double volute can be adopted, or an opposed type blade can be adopted in the case of a plurality of compression stages.

  Furthermore, liquefied nitrogen, liquefied oxygen, LNG, and the like targeted by the low-temperature liquefied gas pump of the present invention have extremely small viscosities compared to general lubricating oils. For example, the viscosity of liquefied oxygen and liquefied nitrogen is about 0.20 cSt. (Stokes, boiling point), which is 1/100 or less of the viscosity of VG32 (32 cSt, 40 ° C.), which is common as a lubricating oil. If the viscosity of the lubricant is low, the ability to form a lubricating film is reduced, and the load capacity of the bearing is reduced.As described above, the thrust force and radial force applied to the bearing can be reduced to keep the pump stable. You can drive.

  Each component such as pump casing, pump main shaft and impeller can be made of low-temperature metal material such as copper, stainless steel or aluminum alloy, and the shape of each component depends on conditions such as pump capacity. According to this, it can be made into an appropriate shape.

  DESCRIPTION OF SYMBOLS 11 ... Pump casing, 12 ... Rolling bearing, 13 ... Pump main shaft, 13a ... Base end part, 13b ... Tip part, 14 ... Magnet coupling, 14a ... Can, 15 ... Motor, 16 ... Inducer, 17 ... First stage Impeller, 17a ... cylindrical seal, 18 ... second stage impeller, 19 ... liquid inlet, 20 ... liquid outlet, 21 ... liquid passage, 22 ... labyrinth seal, 23 ... first bearing holder, 23a ... large diameter disk, 23b ... small diameter disk part, 23c ... pump spindle insertion port, 23d ... step part, 23e ... bearing fitting recess, 23f ... annular groove, 23g ... bolt insertion hole, 24 ... second bearing holder, 25 ... first holder mounting part, 25a ... large diameter disk part accommodating recess, 25b ... small diameter disk part accommodating recess, 25c ... holder mounting surface, 25d ... female screw hole, 26 ... second holder mounting part, 27 ... mounting bolt, 28 ... fixing member, 9 ... alignment pins, 30a, 30b ... pin hole, clearance for S ... thermal expansion absorbing

Claims (3)

  A pump main shaft provided with an inducer and an impeller is rotatably supported inside the pump casing via a pair of rolling bearings, and the pump main shaft rotates, whereby the low-temperature liquefaction sucked into the inducer from the liquid inlet of the pump casing. In a low-temperature liquefied gas pump that boosts gas with the impeller and discharges it from the liquid outlet of the pump casing, a magnet coupling that transmits rotation of a drive source to the pump main shaft and a pair of bearing holders that respectively hold the pair of rolling bearings The pump casing is provided with a pair of holder mounting portions for mounting the bearing holder, and the holder mounting portion and the bearing holder are located at positions where the pump main shaft and the pump casing are coaxial. A pin hole for inserting the alignment pin in the positioned state is formed. Low-temperature liquefied gas pump, characterized in that.   The impeller is a two-stage impeller including a first stage impeller disposed on the inducer side and a second stage impeller disposed on the magnet coupling side, and the pair of rolling bearings is a first stage impeller. A first rolling bearing disposed between the impeller and the second stage impeller, and a second rolling bearing disposed between the second stage impeller and the magnet coupling, wherein the low temperature on the second stage impeller side The liquefied gas is supplied for lubrication of the first rolling bearing through a labyrinth seal that seals the pump main shaft and the pump casing between the second stage impeller and the first rolling bearing, and is supplied from the first rolling bearing to the first stage impeller side. 2. The low-temperature liquefied gas pump according to claim 1, further comprising a liquefied gas passage for lubrication that is discharged to the inside.   The holder mounting portion is a holder housing recess for housing the bearing holder, and a gap for absorbing thermal expansion and contraction is provided between the inner surface of the holder housing recess and the outer surface of the bearing holder. The low-temperature liquefied gas pump according to claim 1 or 2.

Images